Figure 1.— Map of the Connecticut River showing the location of Holyoke Dam and the other 

 dams with fishways on the lower 350 km of the main stem and major tributaries. Dams that 

 sea lampreys can pass are designated by an open bar; dams they cannot pass are designated 

 by a solid bar. 



from 1975 to 1984, they were counted by person- 

 nel from either the Massachusetts Division of Fish- 

 eries and Wildlife or the Massachusetts Cooperative 

 Fishery Research Unit. Until 1975, fish of all species 

 were lifted, deposited into small carts, carried across 

 the dam, and counted as they were released. Begin- 

 ning in 1975, all fish were sluiced directly from the 

 fish lift bucket into a large flume and were counted 

 through a glass window in the side of the flume as 

 they swam upstream. The accuracy of these counts 

 has not been experimentally determined. However, 

 the counts are probably very accurate because the 



sea lampreys are large and swim slowly through the 

 flume. 



We collected sea lampreys daily at the fish lift trap 

 from 1 May to 10 June 1981, and from 10 May to 

 30 June 1982 for determination of total length (TL) 

 and sex. The number of sea lampreys sampled each 

 day was proportional to the number lifted the 

 previous day. The number of sea lampreys lifted and 

 (in parenthesis) the number collected follow: 0-50 

 (2); 51-100 (4); 101-200 (6); 201-400 (8); 401-800 (10); 

 801-1,000 (15); 1,001-2,000 (25); 2,001-3,000 (30); 

 3,001-5,000 (40); >5,000 (50). in both years, total 



477 



